Dynamoelectric machine and processes for making the same

ABSTRACT

Disclosed are methods of making dynamoelectric machines which include use of two sheet metal cup-shaped members to form a housing that completely surrounds and encloses the stator. The stator is assembled with a can in such a manner that the core of the stator is completely contained within the can. Thereafter, a cap is positioned at the exposed face of the stator and the cap and can are joined together by a sheet metal fastening technique which displaces material from one superposed sheet into a second sheet of material. The can and cap are precision formed so that they will have precision sized and located bearing receivers and core retention regions. Both the cap and the can are provided with multiple flange locations which are utilized for fastening the can and cap together during the assembly process. The cap is also provided with a notch which accommodates a lead protecting grommet that preferably is held in place by one or more bosses or pins that are fastened in openings in still another flange formed on the can.

The present invention relates generally to new and improveddynamoelectric machines, such as electric motors, processes ofmanufacturing parts for such machines, and processes for assembling suchmachines.

Dynamoelectric machines, such as electric motors and generators,typically include a stator, a shaft mounted rotor, and a housing orframe parts that hold the stator in a desired place or position and thatalso locate and hold one or more bearings axially centered within thebore of the stator. The one or more bearings in turn receive the shaftand thus support the rotor in the stator bore. Other parts are alsoincluded of course, such as lead wires, lead wire bushings, mountingbrackets, mounting feet or studs, and so forth.

Traditionally, high quality motors having a size of about two and onehalf inches in diameter or larger would be ones that were characterizedas being quiet in operation, having satisfactorily long life, andcapable of being manufactured by processes that have a good yield. Forexample, high quality fan motors made by the assignee of thisapplication, having an outer diameter of about 12.4 cm (about 4.875inches) have long been made by using a housing, two separate end framesor end shields, bearings and lubricating material carried in the endshields, and the requisite rotor and stator assemblies. One particularmodel of this type of motor has included forty-five different pieces orparts and was put together by performing a multitude of differentprocess steps.

Some manufacturers have made motors of this same general size utilizinga smaller number of parts and, apparently, a reduced number of steps.Such other motors sometimes are referred to as "clam shell" motors.Motors of this type known to us involve the use of two cup-like housingmembers that are pressed onto the stator core of a motor from oppositeaxial ends of the stator. The cup-shape members may or may not meet oneanother (that is they may or may not completely cover the outerperiphery of the stator core).

While clam shell type motors as described above are believed to havesignificant quality and performance shortcomings, they do nonethelessrepresent a design approach which, if implemented satisfactorily from aquality standpoint, could represent a significant cost savings ascompared to more conventional approaches. Accordingly, it would bedesirable to provide new and improved methods of assembling motors thatinclude the use of two generally cup-shaped members that both surroundand contain a stator and confine a rotor in a central concentriclocation with respect to the bore of the stator by consistently andaccurately establishing aligned, concentric, relative locations of oneor more bearings and the bore of the stator.

It would be also desirable to provide a new and improved motorconstruction and arrangement of motor parts which could take advantageof the relative simplicity of using two cup-shaped housings for themotor and yet still yield quiet, long lived motors. It would also bedesirable to provide new and improved motor constructions, and methodsof assembling the parts utilized in such construction, which avoid theuse of adhesive materials and yet which rigidly secure various motorparts together while avoiding the application of deforming stresses tothe motor parts (e.g., those associated with welding heat induceddistortions and stresses, and various mechanical stresses).

Accordingly, it is a general object of the present invention to providenew and improved methods of making motor assemblies whereby the abovementioned and other problems may be solved.

It is a more particular object of the present invention to provide newand improved methods of assembling motors that result in a high qualityproduct utilizing relatively few number of parts and relativelyinexpensive assembly techniques.

It is still a further object of the present invention to provide new andimproved electric motors that have the desired features mentioned aboveand which may be advantageously manufactured utilizing the new andimproved methods disclosed herein.

SUMMARY OF THE INVENTION

In carrying out the above and other objects of the invention, in onepreferred form thereof, we provide methods of making new and improveddynamoelectric machines which include the use of two cup-shaped membersto form a housing that may be utilized to completely surround andenclose the stator of the motor. In what is believed to be a significantdeparture from the prior art teachings, we assemble the stator of themotor with one of the cup-shaped members (hereinafter referred to as a"can") in such a manner that the core of the stator is completelycontained within the can. Thereafter, a second cup-shaped housing member(hereinafter referred to as a "cap") is positioned at the exposed faceof the stator and the cap and can are joined together by a fasteningtechnique which avoids or at least minimizes the creation of unbalancedstresses in the cap and can and thus minimizes forces that would tend tocause misalignment of bearings that are carried respectively by the capand can.

In a preferred form described herein, we precisely form the can and capso that they will have precision sized and located bearing receiversthat may be bearing retaining pockets (as illustrated herein). We alsoprovide a precision stator mounting area around an inner peripheralsurface or band of the can. In preferred constructions illustratedherein, we then locate a bearing in the bearing pocket of the can, andpress the stator assembly of the motor into the can so that theferromagnetic core of the stator (which has spaced apart end faces) iscompletely contained within the confines of the can.

The can has a generally cylindrical wall, a first end that carries thebearing receiver and that generally defines a first plane, and an openend that generally defines a second plane generally parallel to thefirst plane. Neither end face of the core is located outside of thespace defined by the generally cylindrical wall and the first and secondplanes. Subsequently, we apply a light grease to the bearing pockets ofboth cup-shaped members, install a wavy washer (if one is to be used) inone of the bearing pockets, dress motor leads at a desired exit locationfrom the can, position the rotor body (with bearings preinstalled onshaft ends) in the bore of the stator and thus the can, and thereafterplace the cap over the stator and rotor and seat a shaft bearing in abearing pocket in the cap. We hold abutting flanges carried by the capand can in superposed position, and fasten abutting or opposing flangestogether by a technique that does not induce the above mentioneddistorting stresses into the cup-shaped members. We have determined thatthe best mode known to us for accomplishing this assembly process is aprocess that is known in the fastening industry as the "TOG-L-LOC®"process, practiced by using tools purchased from the owner of thetrademark. This and similar processes involve a metal displacementprocess whereby a batton of material of one flange is forced or pressedinto the other flange. Thus, the preferred process involves displacingmaterial from one of a pair of abutting flanges into a space formed inthe other of the pair of flanges during the fastening step.

Preferred physical embodiments of our invention disclosed herein includea stator and rotor confined within an enclosure or housing and formedfrom a can and cap, two generally cylindrical walled members that eachhave an open end and a second end that defines a bearing receiver. Suchsecond end will be referred to as a "closed" end, although it may infact have openings therein for ventilation, termination connection, etc.The can is manufactured and dimensioned in two key regions to haveextremely good dimensional accuracy, repeatability, and precision. Thecap is manufactured so as to have one dimensionally precise region. Boththe cap and the can are provided with multiple flange locations whichare utilized for fastening the can and cap together during the assemblyprocess. In our preferred embodiment, the cap is also provided with anotch which accommodates a lead protecting grommet that preferably isheld in place by one or more bosses or pins that are in openings instill another flange formed on the can.

The subject matter which we regard as our invention is set forth in theappended claims. The invention itself, however, together with furtherobjects and advantages thereof may be better understood by referring tothe following more detailed description taken in conjunction with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of a motor embodying the present invention ina preferred form thereof, and which has been made by practicing featuresof our invention;

FIG. 2 is a left-hand front elevation of the motor of FIG. 1 as viewedin FIG. 1;

FIG. 3 is a cross-sectional view, with parts in full, parts in section,and parts broken away, taken along the lines 3--3 in FIG. 2;

FIG. 4 is an exploded perspective view of the parts utilized in themotor of FIG. 1, showing such parts in the condition thereof prior tobeing assembled together;

FIGS. 5 and 6, respectively, are perspective and elevation views of amounting stud, four of which are utilized with the motor in FIG. 1;

FIG. 7 is an enlarged cross-sectional view, with parts broken away, of amounting stud and the part of the cap member that holds such stud;

FIG. 8 is an elevation of a lead protecting grommet used in the motor ofFIG. 1;

FIG. 9 is a view taken in the direction of the lines 9--9 in FIG. 8;

FIG. 10 is a view showing the relationship of the grommet of FIG. 9relative to sections of the cap and can that confine the grommet inplace after assembly;

FIG. 11 is a view, with parts removed, taken along the lines 11--11 onFIG. 10;

FIG. 12 is a view of a modified grommet that may be used instead of thegrommet illustrated in FIGS. 8-11;

FIG. 13 is a view showing all of the parts utilized in the manufactureof a high-quality prior art motor as manufactured for many years by theassignee of the present application; and

FIG. 14 is a view showing all of the parts utilized in the manufactureof the motor illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1-4 we have illustrated an electric motor that embodies ourinvention in a preferred form and that was assembled by utilizing ourpreferred processes.

With particular reference to FIG. 4, it will be seen that the housing(generally denoted at 11 in FIG. 1) of the motor 10 is comprised of afirst part in the form of can 12 and a second part in the form of cap13. The motor further includes a stator assembly 14 formed of aferromagnetic core 16 that has oppositely facing end faces 17, 18 and acentrally disposed bore 19.

The core 16 includes a number of peripheral surface locations 21 thatare arcuate in configuration, and six peripheral surfaces 22 that areflat. The core 16 is made of ferromagnetic (e.g., iron or steel)laminations as is well known in the art.

Stator assembly 14 also includes conventional slot and core insulation,windings that include winding end turns or bundles 23, 24, and windingleads or lead wires 26. The illustrated stator assembly 14 may beessentially any desired prior art assembly, and may have a completelyround outer periphery, only spaced apart arcuate sections as shown, oras would be the case if the laminations were essentially square withrounded corners.

The rotor assembly 27 includes a body shown as a squirrel cage rotorbody 28 fastened to a shaft 29 having two shaft extensions 31, 32 whichproject from opposite sides or ends of the motor (see FIG. 1). While adouble shaft extension motor is illustrated herein, it is emphasizedthat the inventions disclosed herein may be used with equal facilitywith single shaft extension motors or generators.

With particular reference to FIGS. 3 and 4, the rotor assembly 27further includes two ball bearings 33, 34 that are pressed in place onthe shaft. Snap rings 36, 37 snap into grooves 38, 39 in the shaft andare used to define the axial location of the bearings 33, 34. The rotorassembly 27 and wavy or spring washer 41 may be any type conventionallyused in motors and thus further construction details are not presentedherein. It is noted, however, that the inventive processes describedherein and products embodying our invention may be products of typesother than AC induction motors. Thus, it will be readily apparent tothose of skill in the art that our inventive concepts may be applied toDC motors (of the brush or brushless type), universal motors,generators, and alternators.

With continued reference to FIGS. 3 and 4, attention is now directed tocan 12, cap 13, mounting studs 42, and lead grommet 43. Studs 42 aremade of hardened steel and preferably are anchored in holes 44 in cap 13by being pressed therein as suggested by FIG. 7. When this process isfollowed, material 47 in the cap that surrounds the holes 44 in the wall45 of cap 13 is believed to tend to interlock with a circumferentialgroove 48 formed near the head 49. During the pressing operation thatassembles the studs to the cap, serrations 46 bite into the cap wall 45and provide resistance to rotation of the studs about their longitudinalaxis when motor mounting fasteners are threaded onto the stud threads51.

It will be understood by persons skilled in the art that means otherthan studs 42 may be used for mounting motor 10 in a particularapplication. For example, so-called belly-band mounting techniques maybe used. Alternatively and advantageously, holes 52 in the three flanges53, 54, 56 of can 12, and holes 57 in the three flanges 68, 69, 71 ofthe cap 13 may be used (after assembly and securement of the cap to thecan) to accommodate fasteners which fasten the motor 10 to a mountingstructure such as, for example, a bulkhead in a room air conditioner ora separate bulkhead mount type of mounting bracket having a hole throughwhich part of the motor 10 protrudes.

With particular reference now to FIGS. 8-11 and FIGS. 3 and 4, detailsof the lead grommet 43 and its relationship to cap 13, can 12, and leadwires 26 will be described. The grommet 43 (see FIGS. 8 and 4) iscomprised of a mounting base portion 62, lead retaining portion 63 whichhas a closure hook 64, and an integral hinge 66 that joins portions 62and 63 and permits pivotal movement so that the two portions can beclosed, with hook 64 inserted, in latching engagement into hole 66 (seeFIG. 9) in the base portion and thus configure the grommet in a "closedand latched" condition or state.

With particular reference to FIGS. 8, 4, and 10, the base portion 62includes latch members 67 which are used to latch or lock the grommet 43into holes 68, 69 in the flange 71 formed on can 12. During the assemblyprocesses described hereinbelow, a grommet 43 is locked into place on aflange 71, leads 61 are manually positioned and held in the relativeposition depicted by FIG. 10, and the retainer or retaining portion 63is moved to its closed position and latched in place as shown in FIG.10. Thereafter, during one assembly process, cap 13 is assembled withand fastened to can 12, and cut-out 72 accommodates grommet 43. Tofacilitate such accommodation, grommet 43 is provided with side groovesor notches 73, 74 that accept and fit with side edges 76, 77 of the capalong the cut-out 72. The grommet 43 is also provided with a curvednotch or groove 78 that interfits with and accepts the curved edge 79(see FIGS. 10 and 4) of the cut-out 72 in the cap 13.

FIG. 12 illustrates a grommet 81 that is slightly modified as comparedto grommet 43. It will be noted that grommet 81 has all of the samecomponent parts as grommet 43 and, in addition, includes extra materialin the facing portions of base 62 and cover 63 so that round openings 82are defined therebetween. These can be used to relatively tightly trapand retain individual lead wires. When the grommet 81 is used, it may bedesirable to also provide a moisture drain hole in the motor 10 such asa hole indicated at 83 on cap 13 in FIG. 4. With regard to drainage, itis noted that the large lead accommodating opening provided by grommet43 may be also useful for such purpose and drain holes in the motorhousing may be omitted. In preferred embodiments of the invention, thegrommets are molded from a suitable material such as polypropylene.

With reference now to FIGS. 14, 4, and 3, preferred assembly processesand techniques, and further novel structural characteristics andfeatures will be described. Comparison of FIGS. 3, 4, and 14 reveal thatthe motor 10 is an assembly of the 14 different components orsub-assemblies shown in FIG. 14. Our innovative processes, however, donot include the conventional previously described assembly of the sixrotor parts (rotor body, shaft, snap rings, and bearings). Thus, ourpreferred process includes the steps of: mounting the stator assembly 14in the can 12 in a repeatable, precise, and predetermined manner;positioning the rotor assembly with the shaft end 32 extending along abearing receiver such as the opening 84 in the bearing pocket 86, withbearing 34 seated in the interior or cavity of pocket 86, and with theshaft extension 32 nested in a precision bushing and thus held in aprecise, predetermined axial alignment. Initially, the can is looselycentered in a fixture with three pins that fit in holes 52 of theflanges on the can. The bearing 34 has a close tolerance (e.g., aclearance of about 0.005 mm to 0.03 mm) fit with the bearing pocket andthe can and stator (i.e., "canned stator") move or yield to a positionto conform to the location or position of the bearing 34.

Thereafter, we move centering fingers or tools into engagement with thecan at three spaced apart locations that correspond to the location ofthree arcuate locations 21 of the stator core and ensure "centering" ofthe flanged part of the can with the shaft end 32 and bearing 34. Theloose fit between the aforementioned pins and holes 52 permit thenecessary amount of movement.

In the next sequence of steps, we position the cap 13 on the bearing 33with the bearing 33 accommodated in the bearing pocket 87. During thissequence or earlier, the wavy washer is positioned so that it will beretained between the bearing 33 and an interior end wall of the bearingpocket 87 as shown in FIG. 3. In the case of motor 10, the shaftextension 31 protrudes out of the opening in the cap 13 at this step inthe process. However, our process may also be used to assemble singleshaft extension motors, and thus the presence of shaft extension 31 isnot material to our preferred process. As the cap is moved to itsloosely assembled position on the bearing 33, the previously mentionedthree not shown aligning pins fit in the holes 57 in the flanges of thecap, and the flanges 68, 69, 71 of the cap are positioned in facingrelation to the flanges 53, 54, and 55 of the can. Final precisioncentering of all parts next is accomplished by moving one or morefixture surfaces over and axially along the outer diameter 88 of thebearing pocket or retainer 87 (see FIGS. 3 and 4).

The outer diameter or surface 88 of the bearing pocket 87 external hubhas a one degree axial taper, and thus as the centering and assemblyfixture moves along the hub. The hub is progressively centered until thefixture stops moving. This centering action of the bearing hub of thecap in turn causes the bearing 33 and rotor shaft to conform to thecentering action, with the result that the rotor, stator, can, and capare all centered about a central longitudinally extending axis (alongthe rotor shaft) in a precision manner. While the above described partsare all held in alignment as above described, the flanges of the cap andcan are fastened together in a manner to not disturb the centeredalignment of the parts.

In our preferred techniques we fasten the flanges of the cap and cantogether by a process that has become well known in industry as the"TOG-L-LOC®" process by using tools obtained from the BTM Corporation ofMarysville, MI. The BTM Corporation is also believed to be the owner ofthe trademark "TOG-L-LOC®".

When using this fastening technique, metal in the flanges of the cap andcans is displaced and interlocked somewhat as shown at 89 in FIG. 3.With this technique, "buttons" of metal are deformed from two pieces ofmetal and interlocked together without actually cutting a hole all ofthe way through either piece. This type of process appears to bedescribed in a number of U.S. patents assigned to BTM Corporation, mostof which include the inventor E. Sawdon, and all of which areincorporated herein by reference. Some of these patents are: 4,459,735;5,177,861; 5,208,973; 5,208,974; 5,339,509, and 5,435,049. Anotherpatent which appears to describe perhaps a variation of this generaltype of fastening process is U.S. Pat. No. 5,517,743.

Successful practice of the process described above seems to depend onestablishing, with very good precision, consistently sized surfacelocations in three key areas of the can and cap. Those three areas arethe band within the can where the stator fits, and the bearing receiversof the can and cap. More specifically, when following the process stepsdescribed hereinabove, it's important with stamped and formed steelparts, such as the disclosed cap and can, to form the above mentionedthree key areas or regions with consistent precision. For this reason,during manufacture of the can, after the bearing pocket for the can isfirst formed, it is then "re-struck" with tooling to accurately size it.By using re-strikes, the material of the bearing pocket is moved andshaped, so as to be consistently of the dimension of the tooling used inthe last strike. This technique is used to accurately size the side wallinterior of the bearing pocket in the can, the exterior, taperedside-wall of the bearing pocket in the cap, and the interior band of thecan where the stator core is to be pressed. We have found thatexceptionally good results are obtained when the maximum total indicatedrun-out between the stator mounting band and the interior is bearingpocket side wall (in the can) is equal to or less than 0.10 mm.

In preferred embodiments of the invention, we utilized 1.22 mm (0.048in.) thick low carbon steel that was aluminum--Silicon alloy coated andoften simply referred to as "aluminized steel" to make the can and cap.When using this type of material, a number of advantages result. One isthat the product can be sold without being painted for rust or corrosionprevention purposes, and the resulting motor product has a pleasant"silvery" appearance. Also, however, this material is easily paintablewithout expensive pre-painting surface preparation or treatment, andthus manufacturers have the option of painting or not painting theexterior of the product. In addition, the aluminized material readilyexhibits evidence that our "restriking" or "burnishing" or "sizing"techniques are followed. For example, the interior of the can isrelatively bright "silver" in appearance except in the band or areawhere the restriking has taken place. This band is identified by thenumeral 89 in FIG. 4, and it is medium to dark gray in color, andappears to have "striping" marks therealong. Similar types ofdiscoloration and markings also appear on the key bearing pocketsurfaces 88 and the interior surface 91 in pocket 86. In addition theoutside of the can 12 seems to often show (see band 96 in FIG. 4) thelocation of band 89 by having a slightly discolored or burnishedappearance.

It should be noted that the process described herein is a preferred one,but variations could easily be made. For example, the interior of pocket87 could be "sized", and the exterior of pocket 86 could be "sized". Inthat case, however, the rotor would most likely first be positioned inthe cap, and the can and stator would then be placed over the rotor,followed by fastening of the flanges.

A number of product characteristics appear to be helpful in the practiceof our process. For example, it is noted that three flanges are used onthe can and cap. This is helpful for ensuring proper assembly and"squaring" of the stator core and can. In our preferred process, thestator is placed on a locating post to properly locate the center of thestator bore, and the bottom face of the core rests on a true flatsurface perpendicular to the post. The center of the post carries aspring loaded, smaller diameter post onto which bearing pocket 86closely fits, and an upper fixture moves the can down over the stator(i.e., presses the can on the stator) and squares the can relative tothe stator by pressing or pushing on the three flanges close to the sidewalls of the can. As this step is completed, the entire stator core issurrounded by the can, and no peripheral part of the core between itsend faces is exposed to manufacturing forces associated with anysubsequent assembly process step. This part of our process results in asignificant feature of our product. That is, the can and stator core arepressed together until the face of the flanges 53, 54, 55 are bottomedon the same flat surface as the face 17 of the stator. Accordingly, theend face 17 of the stator is essentially co-planar with the faces 92,93, 94 of the flanges. Slated in other words, the bearing receiver endof the can 12 generally defines a first plane at one end of thecylindrical walls of the can, the front of the can flanges 53 (as viewedin FIG. 4) generally define a second plane at the other end of thecylindrical wall, and neither face of the stator core is located outsideof the space defined by the generally cylindrical wall and the first andsecond planes (e.g., see FIG. 3). At this point, it will be appreciatedthat the present inventive concepts could also be applied by having thecore rest on a raised step or ledge in the supporting fixture so thatthe can was pressed to a point such that the plane of the face of thecore was offset from the plane of the flanges. Since none of the corewould project out of the can, the above described conditions would stillbe met.

Other steps may also be used when following our process, and those willnow be pointed in a recapitulation of the process described above.Initially, the can and stator are pressed together as described above.At a grease bench, four to six "dots" of grease are placed on theinterior side walls of the bearing pockets of both the can and the cap,and the relatively viscous grease helps retain the spring washer in thebearing pocket of the cap. Any suitable grease may be used for thispurpose, and we have determined that a grease sold under the trade nameDolium®.

The grommet 43 then is snapped in place on flange 71 of the can, thestator leads are positioned in the grommet, and the grommet is latchedin a closed condition. The can and stator is then placed in a fixture,open end up (with three pins loosely locating the holes 52 in the canflanges); the rotor is placed in the can, with a precision bushingcentering the shaft extension 32; and the shaft, acting through thepreviously pressed in place bearing 34, causes the bearing receiver ofthe can (bearing pocket 86) to be precision centered with respect to theshaft. Three fingers are cammed into placed against band 96 on the canas described above, and the cap is placed over the can, with the bearing33 seating in the bearing pocket of the cap, and the three previouslymentioned alignment pins loosely or roughly aligning the holes 57 in theflanges of the cap. Thereafter, the cap is pressed to a position wherethe flanges of the cap and can mate, and the fastening process describedabove is performed at two locations on each flange (see the six fastener"buttons" 97 in FIG. 2).

By following the process as now described it will be appreciated that amotor of "clam-shell" construction can now be produced that is ofextraordinarily high quality because of the establishment andmaintenance of close alignment and concentricities of key mechanicalelements, and without subjecting those elements to post manufacturing orassembly forces and stresses that cause misalignment.

The parts used in one prior art motor are shown in FIG. 13. Those partsincluded a stator assembly 14, a rotor assembly similar to rotorassembly 27 except that sleeve bearings were used rather than ballbearings, various thrust washers, lubrication slingers, lubricantretainers 101, a rolled steel shell 102, two end frames 103 and fourthrough bolts and nuts. Motors made using the parts shown in FIG. 13 areof very high quality, reliable, and quiet in operation. However, acomparison of FIGS. 13 and 14 quickly reveals the great cost advantage(in terms of both cost and assembly labor or time) associated withproducing clam shell type motors. This comparison also should emphasizethe significance of the process and product innovations presented hereinwhich result in products of such quality, reliability, and performance,that they should be expected to replace motors comprised of the priorparts shown in FIG. 13.

Numerous modifications to our process and product will now becomeapparent to persons skilled in the art. For example, motors with sleevebearings on self-aligning bearings (rather than ball bearings could beproduced). In addition, while the closed ends of the illustrated cap andcan are shown as solid surfaces, ventilation holes or holes for otherpurposes could be provided therein.

Accordingly, while we have now shown and described preferred andalternate forms of preferred embodiments of our inventions; thedisclosure contained herein should be construed as being exemplary, andeach invention itself should be limited only by the scope of the claimsthat are appended hereto and that form part of our disclosure.

What we claim as new and desire to secure by Letters Patent of theUnited States is:
 1. In an electric motor having a stator comprised of aferromagnetic core having opposite end faces and a bore, a two-parthousing containing the stator, at least one bearing supported by thehousing, and a rotor and shaft supported in the bore of the stator bythe at least one bearing, the improvement wherein a first one of thehousing parts has a generally cylindrical wall, a bearing retainer endthat generally defines a first plane at one end of the generallycylindrical wall and an open end that generally defines a second planeat the other end of the generally cylindrical wall and generallyparallel to the first plane, the stator core being contained completelywithin the generally cylindrical wall of the first one of the housingparts so that neither end face of the core is located outside of thespace defined by the generally cylindrical wall and the first and secondplanes, the first one of the housing parts being in the shape of a canhaving the stator core press fit therein, the second one of the housingparts being in the shape of a cap having a generally cylindrical wall, agenerally closed end and an open end, the cap having a leadaccommodating notch provided in the cylindrical wall of the cap at theopen end thereof, the first and second housing parts each including aplurality of circumferentially spaced flanges projecting generallyradially outwardly at the open ends of the can and cap respectively, theflanges of the cap and can generally abutting one another, one of therespective abutting flanges of the can having an opening therein, andthe motor including a lead locating grommet having a latch thatinterfits with the opening and that holds the grommet in a predeterminedlocation with respect to said respective flange.
 2. The invention ofclaim 1 wherein: the first and second housing parts each include threeflanges projecting generally radially outwardly at the open ends of thecan and cap respectively.
 3. The invention of claim 2 wherein theabutting pairs of flanges of the cap and can are fastened to one anotherby a metal displacement process whereby a button of material of oneflange is pressed into the other flange.
 4. The invention of claim 1wherein the first and second housing parts are formed from aluminizedsteel, and at least one precision dimensioned portion of at least onehousing part is associated with coloration variations on the surface ofthe part at the location of such portion.
 5. In an electric motor havinga stator comprised of a ferromagnetic core having opposite end faces anda bore, a two-part housing containing the stator, at least one bearingsupported by the housing, and a rotor and shaft supported in the bore ofthe stator by the at least one bearing, the improvement wherein a firstone of the housing parts has a generally cylindrical wall, a bearingretainer end that generally defines a first plane at one end of thegenerally cylindrical wall and an open end that generally defines asecond plane at the other end of the generally cylindrical wall andgenerally parallel to the first plane, the stator core being containedcompletely within the generally cylindrical wall of the first one of thehousing parts so that neither end face of the core is located outside ofthe space defined by the generally cylindrical wall and the first andsecond planes, the first one of the housing parts being in the shape ofa can, having the stator core press fit within the can, the second oneof the housing parts being in the shape of a cap having a generallycylindrical wall, a generally closed end and an open end, and includinga lead accommodating notch provided in the cylindrical wall of the capat the open end thereof, the first and second housing parts eachincluding three flanges projecting generally radially outwardly at theopen ends of the can and cap respectively with the flanges of the capand can generally abutting one another wherein the can includes a fourthflange having at least one opening therein and the motor includes a leadlocating grommet having a latch that interfits with the at least oneopening and that holds the grommet in a predetermined location withrespect to said fourth flange.
 6. The invention of claim 5 wherein: thefourth flange of the can faces the lead accommodating notch in the cap;the grommet defines grooves that accommodate the edges of the notch inthe cap, and the grommet is interfitted with the cap and located in thenotch.
 7. An electric motor having a stator core with a boretherethrough; a rotor having a shaft and a rotor body disposed in thestator bore; and a two-part housing; said housing comprising a canformed from stamped sheet steel and having precision sized regions forreceiving a shaft bearing and the stator core; said stator and said canbeing press fit together with the stator core contained completelywithin the can; with the bore of the core and the precision sized regionof the can for receiving a shaft bearing being located concentricallywith the rotor, the can including a plurality of circumferentiallyspaced flanges projecting generally radially outward from an open endthereof, one of the flanges including an opening therein foraccommodating an interfitting latch for securing a motor lead locatinggrommet thereto in a predetermined location relative to the flange.